New Study Shows Bariatric Surgery Before Total Knee Replacement May Reduce Complications and Costs for Patients with Severe Obesity

Published in February Issue             

A new study in the Journal of Bone and Joint Surgery shows that patients with severe obesity who have bariatric surgery two years before knee replacement tend to have fewer complications and an improved quality of life, at a cost researchers say is “below the amount society and health care payers, like insurers and government, are typically willing to pay.”

Previous studies have linked obesity to adverse outcomes and increased costs following total knee replacement. According to the American Academy of Orthopaedic Surgeons (AAOS), obesity is a known risk factor osteoarthritis and places total knee replacement patients at increased risk for complications, including delayed wound healing, infection, the need for revision surgery, and lower functional outcomes. In addition, there are technical challenges associated with performing surgery on a patient with obesity, so operative times are
often longer.

Researchers from the Hospital for Special Surgery in New York say this study, which used computer modeling for its analysis, may be the first to compare the cost effectiveness between those who have bariatric surgery before knee replacement and those who don’t. Researchers reviewed previously published data on obesity, bariatric surgery and total
knee replacement.

“We know that bariatric surgery can be an effective treatment for morbid obesity, reducing a patient’s excess weight. In addition, the surgery also reduces the burden of co-morbidities, like diabetes and high blood pressure, and may extend a patient’s life span,” said orthopaedic surgeon and lead study author Alexander McLawhorn, MD, MBA, from the Hospital for Special Surgery in a press statement. “What we didn’t know was whether or not it is cost effective to recommend bariatric surgery to achieve weight loss and improve preoperative health prior to joint replacement.”

The computer model predicts that patients with severe obesity who have bariatric surgery two years before knee replacement are more likely to have an improved quality of life, measured in quality-adjusted life years (QALYs), than patients who only have total knee replacement. A QALY is a metric used to quantify the health benefits generated by a particular treatment.

According to researchers, the cost required to achieve this level of improvement in patients with severe osteoarthritis who require knee replacement, was $13,910 per QALY. QALYs measure both the time patients live after receiving a treatment, and the quality of
their health.

“While there remains some uncertainty in terms of the precise effects of bariatric surgery on knee osteoarthritis and total knee replacement, our model summarizes what is known about the clinical effects and costs of obesity, bariatric surgery and knee replacement,” said Dr. McLawhorn.

The doctor added that the results of new study might help surgeons in counseling patients with severe obesity and knee osteoarthritis in devising individualized treatment plans that include “optimization of overall health, nutrition, and weight prior to knee replacement.”

The study was published in the January 20, 2016 edition of the Journal of Bone and
Joint Surgery

The AAOS points out that patients with obesity may never achieve the increased mobility and range of motion experienced by non-obese patients and that they may also experience more implant and prosthesis complications after surgery, including component loosening and failure, and dislocation of the replacement joint, especially in the hip. According to the Center for Disease Control and Prevention (CDC), about 719,000 total knee replacements are performed each year in the United States.

Raul Rosenthal, MD

“This study shows it makes both health and economic sense for patients with severe obesity and osteoarthritis to strongly consider bariatric surgery before knee replacement,” said Raul Rosenthal, MD, president of the American Society for Metabolic and Bariatric Surgery (ASMBS). “Not only will the knee surgery go better, but the improvements in overall health can be dramatic.”